[gnome-documents/rhel-7.4: 12/16] lokview: Fix crash on repeated open of presentations

[Debarshi Ray <debarshir src gnome org>]

commit 3bd516524432f9decb0a15ab209a9957b7ae7488
Author: Caolán McNamara <caolanm redhat com>
Date:   Mon May 8 16:44:32 2017 +0100

    lokview: Fix crash on repeated open of presentations
    
    Ensure prompt destruction of the LOKDocView widget when the view is
    destroyed. This gives LOK a chance to shutdown at the right time.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=782508

 src/lokview.js |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/src/lokview.js b/src/lokview.js
index 988db96..238832e 100644
--- a/src/lokview.js
+++ b/src/lokview.js
@@ -137,11 +137,19 @@ const LOKView = new Lang.Class({
             this._lokview.connect('text-selection', Lang.bind(this, this._onTextSelection));
             this._lokview.connect('notify::can-zoom-in', Lang.bind(this, this._onCanZoomInChanged));
             this._lokview.connect('notify::can-zoom-out', Lang.bind(this, this._onCanZoomOutChanged));
+            this.connect('destroy', Lang.bind(this, this._destroyView));
         }
 
         return sw;
     },
 
+    _destroyView: function() {
+       if (this._lokview) {
+           this._lokview.destroy();
+           this._lokview = null;
+       }
+    },
+
     onLoadFinished: function(manager, doc) {
         this.parent(manager, doc);
 
@@ -237,10 +245,10 @@ const LOKView = new Lang.Class({
     },
 
     get page() {
-        return this._lokview.get_part();
+        return this._lokview ? this._lokview.get_part() : 0;
     },
 
     get numPages() {
-        return this._lokview.get_parts();
+        return this._lokview ? this._lokview.get_parts() : 0;
     }
 });